1. Technical Field
The present invention is directed to an improved apparatus and method for increasing the reliability of data in microchips by providing an improved signal filter. More specifically, the present invention is directed to an improved and programmable glitch filter.
2. Description of Related Art
In microchip technology, the reliability of data signals in the microchips is an ever-increasing important issue. By reliability what is meant is the amount of certainty that the data signals are not corrupted by noise imparted to the data signal. Noise may be imparted to a data signal from a number of different sources, one of which is crosstalk between signals lines.
A number of solutions are available to assure data validity. One of these methods involves filtering glitches that can lead to corrupt data. With this approach, glitch filters are used to filter out glitches in the data signals.
The known glitch filters are of a fixed depth type. By fixed depth, what is meant is that the glitch filter can only examine the data signal for a fixed, non-adjustable, length of time to determine if a glitch occurs. Another way of saying this is that the glitch filter can filter the data signal for only a fixed, non-adjustable length of time.
For example, if a signal was to be filtered so that glitches of 5 ns or less are filtered out and ignored, then that is all the filter can do. Now, if two signals are to be filtered for different size glitches, one for 5 ns or less and the other for 10 ns or less, two separate filters would have to be designed and implemented. This results in taking more design time and more complexity in the microchip design. Thus, it would be beneficial to have an apparatus and method for filtering glitches that is not limited to a fixed depth. It would be beneficial to have a glitch filter that may be programmed to operate on different glitch depths.
The present invention provides an apparatus and method for filtering glitches in data signals. The present invention provides a programmable glitch filter that may be programmed to filter glitches of different depths. The present invention further provides a glitch filter that is programmable and incorporates a synchronizer for synchronizing the filtered output from the glitch filter to a different clock domain than that of the clock input. These and other features of the present invention will be described in, or will become apparent to those of ordinary skill in the art in view of, the following detailed description of the preferred embodiments.